Heater system for liquid cooled internal combustion engines



R. E. "rHoMAs HEATER SYSTEM FOR LIQUID COOLED INTERNAL COMBQSTIONENGINES Filed Jan.' 25, 1965 INVENTOR.

United States Patent O 3,159,153 WATER SYSTEM FOR LIQUID COULED EJ-TERNAL CDMBUSIION ENGINES Ralph E. Thomas, 44 Hickory, Troy, Mich. FiledJan. 23, 1963, Ser. No. 253,332 12 Claims. (Cl. 12S-142.5)

This invention relates to a liquid coolant circulation system forinternal combustion engines which functions to maintain the engine in aheated condition even during long periods of engine idleness under coldweather conditions. More specically, the subject matter of my inventionis a coolant circulation system for internal combustion engines, whichincludes a coolant heater operative during periods of engine idleness tomaintain the coolant in the engine block at `a predetermined temperaturesucient to expedite cold weather starting.

Various systems have heretofore been proposed for maintaining aninternal combustion engine at a relatively high temperature duringengine idleness in coldweather to expedite starting. One of the Inostcommon of such systems incorporates an electrically heated or a gas orother fuel lire coolant heater with inlet and outlet connected into thenormal coolant circulation system of the engine such that during engineidleness hot coolant can continue to be fed through the engine block tothereby maintain it at a relatively high temperature. In any such systemthere are two main problems. First, there is that of assuring efficientcirculation of the coolant from the heater to the engine block and thenback to the heater. The second problem is that of assuring that thecoolant heater ceases operation once the engine is warmed up. Priorproposed systems are deficient in one or both of these respects.

One of the principal objects of my invention is the provision of asystem of the type described, wherein eilicient circulation `of thecoolant from the heater to the engine block and then back to the heateris accomplished solely by convection. Another object is to provide acoolant heater system which, by reason of the circulation of the coolantbetween the engine block and the heater, assures that the heater remainsinoperative while the engine is in a heated condition. Briefly, theseobjects are accomplished in accordance with the invention by connectingthe coolant heater into the normal engine coolant system in such a waythat there is relatively unrestricted convection induced flow of hotcoolant from the heater to engine during periods of engineinoperativeness, but with the flow of hot coolant being in the directionof the heater lonce the engine is operative and in a fully heatedcondition. A heat-sensing device in thesystem causes the heating elementin the heater to operate only when the temperature of the coolant isbelow a certain predetermined level. Hence, the heater is operative `tomaintain the coolant and therefore the engine warm while the engine isidle and would normally become cold, but becomes inoperative while theengine is operating at its normal temperature. These and other featuresand advantages of the invention will appear more clearly from thefollowing detailed description of a preferred embodiment thereof, madewith reference to the appended drawings in which: FIGURE 1 is a sideelevational fragmentary view, partially schematic, of a preferredembodiment of they invention; and

FIGURE 2 is a view taken on a line 2-2 of FIG- URE l.

"Referring now to FIGURE l, there is shown a liquid- `cooled,reciprocating type internal combustion engine comprising an engine block4 having the normal coolant passages therein, a radiator 6 having topand bottom headers 8 and 1li respectively, and coolant conduits or hoses12 and 14 of conventional about 11/2 diameter,

3,159,153 Patented Dec. 1, 1964 ICC conduit 12 leading from the bottomheader to the engine block and conduit 14 forming a passage from the topof the engine block up to the top header 8. A coolant pump 16 operateswhile the engine is running to pull coolant from the engine block andcirculate it upwardly through conduit 14 to the header 8, down throughthe radiator and thence back to the engine block through the conduit 12.A thermostat 18 at the top of the engine block and in the conduit 14 isoperative to fully open the passage in the conduit when the coolant hasreached a predetermined temperature, say F., the thermostat having apermanently open small passage 20 therethrough which providescommunication between the header 8 and the engine block even when thecoolant is below 180 F. 4and the thermostat is in its closed position.The top header of the radiator is provided with a filler opening havinga pressure radiator cap 22, of conventional construction, to maintain apressure in the coolant system of about 3 to 4 pounds per square inch,or even higher, above normal atmospheric pressure while the engine isrunning. It will be noted that as thus far described the coolantcirculation system shown is conventional though, as will be seen fromthe following further description, some of the components thereofperform functions in accordance with the present invention which are inaddition to and different from their normal functions.

In accordance with the invention, the system shown includes a coolantheater 24 which comprises an outer generally box-shaped metal shell 26,a gas pilot light and burner assembly 28 with a coolant temperaturesensitive control 30 and a coolant heating chamber 32 positioned abovethe gas burner assembly. The chamber 32 has a conduit 34 of about 3A"diameter communicating with the engine block and another conduit 36 ofthe same diameter extending upwardly and communicating with lthe topheader 8 of the radiator. Metal housing 26 is provided with suitable airinlets 38 to provide ample oxygen for the burner 28 and with an outlet40 at the top to allow exit of the exhaust gases from the burner. A fueltank 42 for the burner is suitably mounted on the fire wall of thevehicle and has a fuel feed line 44 leading to the burner controlmechanism 30. In this particular embodiment, butane gas is used to fuelthe burner; however it will be understood that other gases or liquidfuels, or even an electric resistance heating element, can be used forthe heater if desired. The burner-pilot light assembly can be ofconventional well-known construction, the precise details of thisassembly forming no part of the present invention. Control 30 has a maingas feed line 45 which leads to the main burner and a small feed line 48leading to the pilot light. A fail-safe control device 50, also ofconventional construction, leads back'to the control mechanism 30 toassure that the gas flow to the pilot light is cut off in the event thepilot light goes out. Control 30 includes a heat-sensing element 52having its heat-sensing portion in the coolant chamber 32 adjacent theopening for conduit 34, such heat-sensing element being operativethrough the control mechanism to regulate the ow of gas 'to and hencethe ignition of the main burner so as to maintain the coolant above apredetermined temperature. A regulator, indicated at 54, is provided on`the control 30 so that the predetermined temperature can be set. Suchheat-sensitive burner controls are well known, and the precise detailsof construction thereof form no part of the present invention. In theparticular control shown, the heat-sensing element comprises aheat-expansible metal rod which has an end threadedly supported adjacentthe end of conduit 34 in the interior of the heating chamber 32, and apointed oppositely disposed end which projects into the controlmechanism 30, the pointed or tapered end serving as a valve for the flowof gas into the tube 46 which communicates with the burner. Moves, 1 es,1 53 ment of the regulator 54 to the desired predetermined minimumtemperature for the coolant rotates the rod such that its threadedconnection determines the length thereof and hence the amount of heatrequired to induce elongation to the extent that the pointed end closesthe gas flow line 46. As indicated above, the details of this mechanismform no part of the presen-t invention, and any other suitableheat-sensing control device for actuating the burner may be used ifdesired.

It will be noted that the coolant heating chamber 32 is loca-ted belowthe horizontal level of the radiator header 8 such that the conduit 36must extend generally upwardly from the heating chamber to the header.Further, and as can best be seen in FIGURE 2, it will be noted that theopening 56 for the conduit 36 into the top header is positioned justabove the horizontal center line of the opening 58 for the conduit 14which leads to the header from the engine block. For reasons which willbe evident from the following description of the operation of thesystem, ythese are important features of the invention.

Operation of the system is as follows: Assume first that the truck, bus,or other vehicle in which the system is being used is parked outdoors ona cold winter night, f

.and hence is exposed to a temperature well below freezing. Assumefurther that the control 30 for the heater has been given a setting of50 F. After the vehicle has been parked for a short time with the engineshut off, the coolant temperature will drop down to 50 F., at which timethe control 30 will operate to light the burner `and hence heat thecoolant in the chamber 32. As the coolant in the lchamber 32 becomesheated, normal convection lwill cause the heated coolant to rise throughthe `conduit 36 and into the header 8 through the yopening 56. Referringto FIGURE 2, it will be noted that the liquid level in the header atthis time, with the engine inoperative and the coolant temperaturerelatively low, is about on the horizontal line of the opening 58, thisbeing .the normal idle engine coolant level for the reason hereinafterspecied. Hence, the opening 56 is above the -liquid level and opens intothat portion of the header which is occupied by simply air or watervapor For ythis reason, the hot coolant moved by convection up the pipe36, can empty freely into the header 8 without the blocking effect orresistance which `would occur if the opening 56 were below the liquidlevel. The hot coolant emptying from the opening 56 into the header isthen free to oW through opening 58 down through the conduit 14, throughthe opening 20 in the thermostat and into the engine block. Suchcirculation causes coolant to flow out of the engine block throughconduit 34 and into the heating chamber 32. Hence, circulation ofcoolant from the heater to `the header 8 through the engine block andthen back to the heater continues until the temperature of the coolantrises above 50 F., at which ltime the control 30 causes the 'burner tocease operation until the coolant temperature drops below 50, at whichtime the above cycle repeats. In this way the temperature of thecoolant, `and therefore the temperature of the engine block, .ismaintained at about 50 F., irrespective of the length of time thevehicle stands idle.

When the engine is started, which starting is quite easy ybecause theengine hasbeen maintained in a heated rcondition, the thermostat 18 willbe in its closed position, and 'hence the pump 16 Will cause circulationof the coolant from the radiator, through the bottom header thereof, tothe engine block and thence through the conduit 34, heating chamber 32and conduit 36 back to 'the radiator, lsome slight amount of circulationpossibly also being caused through the small opening 20 in thethermostat. Rather shortly after the engine has commenced operation, theliquid level in the header rises above the `bottom of opening 56, thisrise in liquid level always occurring because of the expansion of thecoolant as it becomes heated, and

also because of the ebullition in the system caused by sure builds up inthe upper header due `to the pressure cap closure 22. Assuming a F.thermostat is being used, when the coolant reaches this temperature thepump 16 causes normal coolant circulation between the radiator and theengine, i.e., circulation from the bottom of the radiator through theengine block and thence through the conduit 14 to the top header andagain through the radiator. When the system reaches such condition,since the liquid level in the header is above opening 56 and since thereis pressure in the header, hot coolant from the header is caused to alsoflow downwardly through conduit 36 in the direction of the heater andinto the heating chamber 32. By means 'of this reverse flow of coolantinto the heater when the engine is in a normally heated condition, thecoolant in the heating chamber 32 remains well above 50 F., and hencethe burner will remain inoperative during the entire period of continuedengine operation and until the vehicle is again allowed to stand idlefor suiiicient period to cause the coolant temperature to drop below 50F. The reverse ow feature has the special advantage of assuring that thecoolant in the heating chamber 32 will be at close to the sarnetemperature as that in the engine block when the vehicle is parked andthe engine shut off.

As indicated above, the liquid level in the system will be such thatwhen .the engine is cool it willbe at about the horizontal center lineof the opening 58, and when hot will rise to the level of the opening56. This is normal since the radiator header is provided with aconventional overflow pipe 60 (see FIGURE 2) located aboverthe opening58, and also slightly above the opening 56. Hence, the liquid level evenwith the engine running is never substantially above opening 56 andnormal cooling causes the liquid level to dr-op slightly below opening56 when the engine is idle.

As indicated above, the heating chamber 32 must be located below thehorizontal level of the header 8. Actually, it has been found highlydesirable for optimum eiiciency, that the chamber 32 be positioned asvlow as practical and preferably below the connection of conduit 34 withthe engine block.

It will be readily apparent that the present invention is easilyadaptable to engines of diifering configurations than that shown in thedrawing. For example, should the radiator of the engine be disposedbelow the upper level of the engine block, the outlet conduit from theheater tank would communicate with the top of the block rather than withthe radiator header. This would be so since it is important to have such.conduit communicate with the cooling system of the engine slightlyabove the highest vlevel therein.

It will be evident from the above description that the presentVinvention provides a coolant heater .and circulation system whichaffords optimum eiciency in maintaining the engine warm during periodsof idleness, while at the same -time assuring against unnecessary heateroperation while the engine is hot.

While the invention has been described specically with reference to apreferred embodiment it will be understood that various changes andmodications can be made all within the full and intended scope of theclaims which follow.

I claim:

1. A liquid coolant heater for an internal combustion engine having aliquid coolant circulation system comprising a coolant heating chamberhaving two conduits communicating with the engine coolant circulationsystem to allow circulation of the coolant through the heating chamber,heating means for the coolant in said charnber, and kcontrol means foractuating said heating means when the coolant temperature ydrops `belowa predetermined temperature, one of said conduits from the heatingchamber communicating with the -engine coolant system below the upperlevel of the coolant in said system for ilow of coolant therethrough andthe other said conduits communicating with the engine coolant system ata level which is above that of the coolant in said system when theengine is inoperative and the coolant is below said predeterminedtemperature for flow of coolant therethrough.

2. A liquid coolant heater for an internal combustion engine having aliquid coolant circulation system cornprising a coolant heating chamberhaving two conduits communicating with the engine coolant circulationsystem to allow passage of coolant through the heating chamber, saidheating chamber being located below the upper level of the liquidcoolant in the circulation system, heating means for the coolant in saidchamber, and control means for actuating said heating means when thecoolant temperature drops below a predetermined temperature, one of saidconduits extending upwardly from the heating chamber and vcommunicatingwith the engine coolant system below the upper level of the coolant insaid system and permitting coolant flow therethrough and the other saidconduits communicating with the engine coolant system at a level whichis above that of the coolant in said system when the engine isinoperative and the coolant is below said predetermined temperature topermit coolant flow therethrough.

3. A liquid coolant heater for an internal combustion engine having aliquid coolant circulation system which includes a radiator with a toplheader, said heater comprising a coolant heating chamber located belowsaid header and having two conduits communicating with the enginecoolant circulation system to allow passage of the coolant through theheating chamber, heating means for the coolant in said chamber, andcontrol means for actuating said heating means when the coolanttemperature drops below a predetermined temperature, one of saidconduits from the heating chamber communicating with the engine coolantsystem below the upper level in the coolant in said system audpermitting coolant flow therethrough and the other of said conduitscommunicating with said header at a level which is above that of thecoolant in said header when the engine is inoperative and the coolant isbelow said predetermined temperature to permit coolant ow therethrough.

4. A liquid coolant heater for an internal combustion engine having aliquid coolant circulation system comprising a coolant heating chamberlocated below the upper level of the coolant in said system and havingtwo conduits communicating with the coolant circulation system to allowpassage of the coolant through the heating chamber, heating means forthe coolant in said chamber, and control means for actuating saidheating means when the temperature of the coolant in said heatingchamber drops below a predetermined temperature, one of said conduitsfrom the heating chamber communicating with the engine coolant systembelow the upper level in the coolant in said system and permittingcoolant ow therethrough and the other said conduits communicating withthe engine coolant system at a level which is above that of the coolantin said system when the engine is inoperative and the coolant is belowsaid predetermined temperature to permit coolant flow therethrough.

5. A liquid coolant heater and circulation system for a liquid-cooledinternal combustion engine comp-rising an engine block having liquidcoolant passages therethrough, a radiator communicating with said engineblock to allow circulation of coolant therebetween, a coolant heaterwith a coolant heating chamber therein and conduits providingcommunication between said heating chamber and said radiator and engineblock, said conduits being arranged to cause circulation of liquidcoolant through the heating chamber in one direction when the coolant inthe heating chamber is at a higher temperature than that in the engineblock and to cause circulation of the coolant into the heating chamberin the reverse direction when the coolant in the engine block is at ahigher temperature than that in the heating chamber.

6. A liquid coolant heater and circulation system for a liquid-cooledinternal combustion engine comprising an engine block having liquidcoolant passages therethrough, a radiator with a top header locatedabove the top level of the engine block and communicating with saidengine block to allow circulation of coolant therebetween, a coolantheater with a coolant heating chamber therein located below the level ofsaid header and having conduits providing communication between theheating chamber, the header, and the engine block, said conduits causingcirculation of liquid' coolant through the heating chamber in onedirection when the coolant in the heating chamber is at a highertemperature than that in the engine block and causing circulation of thecoolant into the heating chamber in the reverse direction when thecoolant in the engine block is at a higher temperature than that in theheating chamber.

7. A liquid coolant heater and circulation system for a liquid-cooledinternal combustion engine comprising an engine block having liquidcoolant passages therethrough, a radiator with a top header having anopening located above the engine block and communicating with the engineblock to allow circulation of coolant between the engine block and theradiator, said header having another opening located above saidiirst-mentioned opening, a coolant heater with a coolant heating chambertherein located below said header, a conduit communicating between saidheating chamber and said engine block and permitting coolant dowtherethrough, and a conduit communicating between said heating chamberand the secondmentioned opening in said header and permitting coolantflow therethrough.

8. A liquid coolant heater for an internal combustion engine of the typehaving an engine block, a radiator with a header at the top thereof, andmeans for circulating liquid coolant between the block and the radiatorincluding a conduit extending upwardly from the block to the header andcommunicating with the header through an opening in the side wallthereof, said heater comprising a liquid coolant heating chamber, aconduit extend-V ing upwardly from said chamber and communicating withsaid header through a second opening therein and permitting coolant iiowtherethrough, said second opening being located above the horizontalcenter line of said irstmentioned opening, and a conduit communicatingbetween said chamber and the engine block and permitting coolant flowtherethrough.

9. An internal combustion engine liquid coolant circulation and heatingsystem comprising an engine block, a radiator with a header at the topthereof, said header having a side wall with an opening therein, aconduit communicating between the bottom of said radiator and the blockto allow the coolant to pass from the radiator to the block, a returnconduit extending upwardly from said lblock and communicating with saidheader through the opening in the side wall thereof to allow the coolantto pass from the block to the radiator, coolant heater having a coolantheating chamber with one end thereof communicating with the engine blockand permitting coolant tlow therebetween, a conduit extending upwardlyfrom the other end of said coolant heating chamber to said header andcommunicating with said header through a second opening in the side wallthereof and permitting coolant flow therebetween, said second openingbeing positioned above the horizontal center line of said firstmentionedopening, and means in said heater causing it to operate to heat thecoolant in said chamber when the coolant temperature drops to apredetermined level.

l0. A liquid coolant heater for an internal combustion engine of thetype having an engine block, a radiator with a header at the topthereof, land means for circulating liquid coolant between the block andthe radiator including a conduit extending upwardly from the block tothe header and communicating with the header through an opening in theside wall thereof, said heater comprising a chamber for circulating theliquid coolant therethrough, heating means for said chamber, means forcontrolling said heating means in accordance with the temperature of theliquid coolant in said chamber, a cond-uit extending upwardly from saidchamber and cornmunicating with said header through a second openingtherein Iand permit-ting coolant flow therebetween, said second openingbeing located above the horizontal center line of said rst-mentionedopening, and a conduit cornmunicating between said chamber yand theengine lblock and permitting coolant iow therebetween.

1l. An internal combustion engine liquid coolant circulation and heatingsystem comprising an engine block, a radiator with a header at the topthereof, said header having a side wall with an opening therein, aconduit communicating between 'the bottom of said radiator and the blockto allow the coolant to pass from the radiator to the block, a returnconduit extending upwardly from said block and communicating with saidheader through the opening in the side wall thereof to allow the coolantto pass from the block to the radiator, a thermostat in saidsecond-mentioned conduit operative to fully open said conduit to thepassage of coolant when said coolant reaches a predetermined temperatureand having a permanently opened restricted passage therethrough, a pumpon said engine block to .cause the coolant to circulate through saidconduits between said block and said radiator while the engine isoperating, a hydrocarbon fuel-fired coolant heater having a coolantheating chamber with one end thereof communicating with the engineblock, a pipe extending upwardly from the other end of said coolantheating chamber to said header and communicating with said headerthrough a second opening in the side Wall thereof, said second openingbeing positioned above the horizontal center line of saidfirst-mentioned opening, and means in said heater causing it to opera-teto heat the coolant in said chamber when the temperature of said coolantdrops to a predetermined level.

12. An internal combustion engine liquid coolant circulation and heatingsystem comprising an engine block, a radiator with a header .at the topthereof, said header having a side wall with `an opening therein, aconduit communicating between .the bottom of said radiator -and theblock to allow the coolant to pass from the radiator to the block, areturn conduit extending upwardly from said block and communicating withsaid header through the opening in the side wall thereof to allow thecoolant to pass from the vblock to the radiator, a thermostat in saidsecond-mentioned Vconduit operative to fully open said conduit to thepassage of coolant when said coolant reaches a predeterminedltemperature and having a permanently opened restricted passagetherethrough, a pump on said engine block to cause the coolant tocirculate through said conduits between said block and said radiatorWhile the engine is operating, a coolant heater having a coolant heatingchamber with one end thereof `communicating through an upwardlyextending conduit with the4 engine block, aconduit extending upwardlyfrom the other end of said coolant heating chamber to said header andcommunicating with said header through a second opening in the side-wall thereof, said secon-d opening being positioned `above thehorizontal center line of said iirstmentioned opening, means for heatingthe coolant in said chamber, and heat-sensitive means in said chamber toactuate said heating means when the temperature of the coolant in thechamber drops to a predetermined level.

References Cited in the tile of this patent UNITED STATES PATENTS

1. A LIQUID COOLANT HEATER FOR AN INTERNAL COMBUSTION ENGINE HAVING ALIQUID COOLANT CIRCULATION SYSTEM COMPRISING A COOLANT HEATING CHAMBERHAVING TWO CONDUITS COMMUNICATING WITH THE ENGINE COOLANT CIRCULATIONSYSTEM TO ALLOW CIRCULATION OF THE COOLANT THROUGH THE HEATING CHAMBER,HEATING MEANS FOR THE COOLANT IN SAID CHAMBER, AND CONTROL MEANS FORACTUATING SAID HEATING MEANS WHEN THE COOLANT TEMPERATURE DROPS BELOW APREDETERMINED TEMPERATURE, ONE OF SAID CONDUITS FROM THE HEATING CHAMBERCOMMUNICATING WITH THE ENGINE COOLANT SYSTEM BELOW THE UPPER LEVEL OFTHE COOLANT IN SAID SYSTEM FOR FLOW OF COOLANT THERETHROUGH AND THEOTHER SAID CONDUITS COMMUNICATING WITH THE ENGINE COOLANT SYSTEM AT ALEVEL